This invention relates to an X-ray photographing machine in which a number of unexposed sheet films are taken out one by one from a supply magazine containing such films, and carried into a film carrier in a stand-by position by means of a feed mechanism, the carrier is moved from the stand-by position to an exposure position, where it is exposed to X-rays for X-ray photographing and returned to the stand-by position, and then the film is carried into an exposed film takeup magazine by means of the feed mechanism.
Having various advantages, such as faster operation and ease of post-photographing treatment, over those which employ roll films or films each contained in a holder of their own, X-ray photographing machines using such sheet films or cut films have recently come to enjoy wider use.
Nevertheless, conventional machines of this type have hitherto been subject to several shortcomings, requiring positive improvement. As a premise for the description of this invention, therefore, there will now be described in brief a prior art X-ray photographing machine using sheet films and problems involved therein.
FIG. 1 shows an outline of the prior art X-ray photographing machine using sheet films. In this drawing, there are shown a movable frame a of the machine, a support frame b to support the frame a, a table top c bearing an examinee d, an X-ray source e, and an image intensifier f disposed on the opposite side of the examinee d to the X-ray source e and mounted on the movable frame a.
The movable frame a is capable of general rotation round the examinee d in a body with the support frame b as indicated by an arrow g, slide movement in the longitudinal direction of the examinee d (or at right angles to the plane of the drawing), and vertical motion as indicated by an arrow h independent of the support frame b, whereby the movable frame a approaches and goes away from the examinee d.
A rectilinear path j for a film carrier i defined inside the movable frame a, and the carrier i is normally located in a stand-by position 1 at a considerable distance from an exposure position k. A film supply magazine m and a film takeup magazine n are disposed on the opposite side of the stand-by position 1 to the exposure position k. Unexposed sheet films p in the supply magazine m are drawn out one by one by means of a vacuum sucker q, and delivered into the carrier i by means of paired rolls r. Exposed films are collected from the carrier i returned to the stand-by position into the takeup magazine n through a guide path s by means of the paired rolls r. A transfer plate t is switched with every forward or reverse feed.
In the prior art machine of FIG. 1, the movable frame a is relatively long, since the magazines m and n are disposed substantially on the extension of the carrier path j, that is, they are in line with the stand-by position 1 and the exposure position k, and that the space between the stand-by position 1 and the exposure position k is made considerably wide enough to prevent the unexposed film in the carrier i from what is called X-ray fog in the stand-by position.
Such elongated movable frame a would present the following problems.
(1) Since the movable frame a forms a cantilever structure on the support frame b, the longer the frame a, the greater the demand for the strengthening of the connection between the movable frame a and the support frame b, as well as of the frame a itself, and for the complicated structure and increased overall machine size. In particular, mounted near the free end of the frame a weighing considerably heavy, the image intensifier f has a great influence on the frame structure.
(2) Since the space between the stand-by position 1 and the exposure position k is wide, the transfer distance of the carrier i is long, thus increasing loss of time for the transfer. As a result, many opportunities of photographing may probably be missed.
As for the magazines m and n, they involve the following problems. That is, as mentioned before, the movable frame a is located in positions at varied angles for the photographing of the examinee d from different angles. In some shots, for example, the frame a may be turned through an angle of 180.degree. from the position of FIG. 1, that is, inverted. In such position, openings u and v of the magazines m and n are to face downward. Accordingly, the sheet films p may possibly slip out of the magazines through their openings or bend to cause a handling mistake, so that correct and secure handling of films could not be expected.